This invention relates to systems of the type that are intended to treat solid, granular and aggregate material, and, more particularly, to a system embodying a combination thermal reclaimer and sand-to-sand heat exchanger apparatus in which there is accomplished the treatment by thermal reclamation of material, e.g., reclaiming spent chemically bonded foundry sand and clay bonded foundry sand.
As evidenced by a reference to the prior art, there have been attempts made previously in an effort to treat material by thermal reclamation. In this regard, the focus of one of these prior art attempts has been on an effort to effect the reclamation of foundry sand. One rationale behind this effort has been that if it were to prove possible to effect a recycling of the foundry sand, this would go far towards forestalling the exhaustion of existing sources of supply of foundry sand. Furthermore, to the extent that recycling of the foundry sand takes place at or in relatively close proximity to the individual foundry sites whereat the use was originally made of the foundry sand, the effect thereof would be to negate substantially, if not totally, the need to incur the expenses associated with the transportation of foundry sand from the sources of supply thereof to the foundry sites. In addition, the ability to reclaim used foundry sand obviates the problem associated with the need to find a suitable disposal site for the used foundry sand.
Insofar as the reclamation of used foundry sand is concerned, there are at least two major requirements, which from a practical standpoint, must be satisfied thereby. Namely, the used foundry sand after being subjected to the reclamation process must be in substantially the same condition as it originally was. That is, the reclamation process must be capable of returning the used foundry sand, in essence, to its original condition. Secondly, the reclamation of used foundry sand must be capable of being accomplished economically. More specifically, the cost of reclamation must be such that reclamation from a financial standpoint is sufficiently attractive to render it desirable to undertake the investment in terms of time, labor and money required thereby as compared to continuing to purchase new, i.e., not previously used, foundry sand.
With respect to this matter of the reclamation of used foundry sand, a variety of different types of apparatus have been proposed for use. These apparatus may, for ease of reference, be classified into categories according to the type of treatment to which the used foundry sand is subjected for purposes of effecting the reclamation thereof. Thus, one category of such apparatus is that of mechanical units. Here, reliance is had, generally speaking, on some form of abrasive action in order to effect the removal of, for example, organic coatings from the particles of sand. This abrasive action may be realized through the action of some sort of mechanical member, or through the use of a so-called "air scrubber". The latter refers to a type of device wherein the sand particles are accelerated to relatively high velocities by means of compressed air such that a rubbing action is caused to occur between individual particles of sand. In other instances, the sand particles after being accelerated are made to impinge against a suitably selected surface such that as a result of this impingement the coating fractures and separates from the individual sand particle. For purposes of illustration of a mechanical unit which has been proposed in the prior art for use in connection with the reclamation of foundry sand, reference may be had to U.S. Pat. No. 4,283,015 that issued on Aug. 11, 1981. This patent depicts an apparatus which is intended to be employed for purposes of removing no-bake coatings from foundry sand.
A second category into which such apparatus may be placed, and the one into which the system of the present invention falls, is that of thermal units. In accord therewith, heat is employed for purposes of accomplishing the removal of organic coatings from the sand particles. By way of exemplification in this regard, there has previously been issued on Aug. 22, 1972 to the Applicant of the present invention U.S. Pat. No. 3,685,165. The latter patent is directed in particular to an apparatus for thermally reclaiming resin coated sand. More recently, U.S. Pat. No. 4,429,642 was issued on Feb. 7, 1984 to the Applicant of the present invention directed to another form of thermal reclaimer apparatus. In accord with the teachings of this latter issued patent, there is provided an apparatus embodying rotatable chamber means in which the foundry sand that is to be reclaimed is heated to a predetermined temperature for a preestablished period in order to accomplish the burning away of the organic matter that the used foundry sand contains. Yet still another form of thermal reclaimer apparatus can be found described and illustrated in U.S. patent application Ser. No. 521,495 which was filed on Aug. 8, 1983 in the name of the Applicant of the present invention. In this latter pending patent application there is disclosed a sand reclamation system embodying a thermal reclaimer means which in turn consists of a pipe reclaimer apparatus that has cooperatively associated therewith an air blower and a burner. The air blower and burner are operative to generate a sufficient amount of high temperature gas to effect the transport of the used foundry sand through the pipe reclaimer apparatus at a predetermined velocity. In the course of being conveyed through the pipe reclaimer apparatus organic matter contained in the used foundry sand is burned away.
It is deemed important to make mention here of the fact that the impression should not be had that in order for one to provide a system for effecting the reclamation of used foundry sand, there is a need to be concerned only with the matter of removing organic coatings from sand particles. For, depending upon the condition of the foundry sand that it is desired to reclaim, which in turn is a function of the manner in which the foundry sand has been used, a number of other considerations may be of equal, if not greater, importance. For example, significant amounts of used foundry sand are produced during foundry operations wherein the used foundry sand is replete with organic matter, metal, dust and fines.
As regards the matter of the thermal reclamation of used foundry sand, and in particular that kind of foundry sand which has organic matter, metal, dust and fines present therein, there are a number of factors to which it is desirable that consideration be given if a thermal foundry sand reclamation system is to be provided that will prove to be viable from a commercial standpoint. More specifically, such a thermal foundry sand reclamation system must be capable of accomplishing the removal of the organic matter from the used foundry sand while at the same time leaving the metal that is also present in the used foundry sand in such a form as to enable it subsequently to be readily removed. Thus, one of the factors that must be taken into account in this regard is that of being able to provide sufficient heat to the used foundry sand so that the organic matter present therein is burned away. However, the operating characteristics of the thermal system must be such that the used foundry sand is not heated excessively, i.e., to such a high temperature that the heat produced is sufficient to effect a change in the state of the metal which is present in the used foundry sand. To this end, such a thermal system for reclaiming used foundry sand must possess the capability of enabling the organic matter to be burned away, while at the same time this is being accomplished ensuring that the metal, be it of a ferrous or nonferrous nature, which the used foundry sand contains, is not adversely affected, i.e., rendered more difficult to remove, as a consequence of being exposed to the heat that is employed to burn away the organic matter. In this regard, note is taken here of the fact that some nonferrous metals, e.g., aluminum and zinc, have a significantly different melting temperature than do ferrous metals, and consequently must be treated differently from a temperature standpoint.
Another factor which must be borne in mind when one attempts to provide such a thermal system for reclaiming used foundry sand which contains organic matter, metal, dust and fines is that of the nature of the treatment which should be accorded to the fumes that are generated as the organic matter is being burned away. There are two aspects to this. The first is that of ensuring that such fumes do not pose a danger to the personnel who are attending to the operation of the thermal foundry sand reclamation system. The second is that of ensuring that any fumes which may be exhausted to the atmosphere do not constitute a source of pollutants. That is, the fumes which are exhausted to the atmosphere as a consequence of the operation of such a thermal system for reclaiming used foundry sand should not violate the regulations applicable thereto as established by the local, state and federal authorities having cognizance thereover. The third factor to which it is essential that consideration be given in providing such a thermal foundry sand reclamation system is the matter of the cost thereof. Namely, both in terms of originally providing the system and in terms of operating the system thereafter, the expenditures required thereby must be such as to render it desirable to undertake the requisite investment as compared to continuing the expenditure of the funds necessary to acquire new, i.e., virgin, foundry sand rather than reclaimed foundry sand.
Related to this matter of cost, which is addressed in the preceding paragraph, is the matter of the production output of reclaimed foundry sand that can be realized through the use of such a thermal foundry sand reclamation system. Reference is had here to the fact that for such a thermal foundry sand reclamation system to be commercially viable, it is necessary that the system embody the capability of providing reclaimed foundry sand in the desired quantities, i.e., in amounts sufficient to meet the need therefor as it exists at any given site at which foundry operations capable of making use thereof take place.
The salient point which the preceding discussion serves to make is the fact that there already has been shown to exist in the prior art a need for a system which is operative to effect the reclamation of used foundry sand. In particular, the previous discussion evidences a need in the prior art for a system that is operative to reclaim used foundry sand which contains metal of either a ferrous or nonferrous nature, organic matter, dust and fines. Furthermore, one of the principal components that any such system for reclaiming used foundry sand includes is the apparatus by means of which the organic matter that the used foundry sand contains is thermally removed therefrom; namely, a thermal reclaimer apparatus.
In summary, a need has been demonstrated in the prior art for a thermal sand reclamation system which embodies a new and improved form of thermal reclaimer apparatus that is suitable for use for purposes of effecting the thermal removal of organic matter from used foundry sand. Some of the other characteristics which it would be desirable for such a new and improved thermal reclaimer apparatus to embody would be that of enabling significant energy savings to be realized therewith as well as that of enabling the elimination to be had therewith of some of the components that have heretofore been deemed to be essential for the successful operation of prior art forms of thermal reclaimer apparatus. Lastly, it would also be desirable to provide a new and improved form of feeder means embodying a construction which would render it operative for purposes of feeding granular material into a pipe-like member in a dispersed manner as well as suitable for purposes of being cooperatively associated with the aforesaid new and improved thermal reclaimer apparatus in the aforereferenced thermal sand reclamation system.
It is, therefore, an object of the present invention to provide a system for treating solid, granular and aggregate material which embodies therein reclaimer means for effecting the thermal removal of matter from the material.
It is another object of the present invention to provide a new and improved form of thermal reclaimer means which comprises a first portion of a unitary structure that in turn constitutes one of the operating components of a system for treating solid, granular and aggregate material to effect the thermal removal of matter therefrom.
It is still another object of the present invention to provide a new and improved form of heat exchanger means which comprises a second portion of which a thermal reclaimer means forms the first portion of a unitary structure that in turn constitutes one of the operating components of a system for treating solid, granular and aggregate material to effect the thermal removal of matter therefrom.
A further object of the present invention is to provide a new and improved combination thermal reclaimer and sand-to-sand heat exchanger apparatus which is particularly suited for employment in a system for treating solid, granular and aggregate material to effect the thermal removal of matter therefrom.
A still further object of the present invention is to provide a system embodying a new and improved combination thermal reclaimer and sand-to-sand heat exchanger apparatus, which is characterized in that significant energy savings are capable of being realized therewith and in that the elimination can be had therewith of some of the components that have heretofore been deemed to be essential for the successful operation of prior art forms of thermal reclamation systems.
Yet a further object of the present invention is to provide a system for treating solid, granular and aggregate material to effect the thermal removal of matter from the material which embodies a new and improved form of feeder means operative for feeding material in a dispersed manner into a receiving means.
Yet another object of the present invention is to provide a system for treating solid, granular and aggregate material to effect the thermal removal of matter from material which embodies a new and improved combination thermal reclaimer and sand-to-sand heat exchanger apparatus and a new and improved feeder means, and which is characterized in the fact that it is easy to employ, is reliable in operation, yet is relatively inexpensive to provide.